1. Field of the Invention
This invention relates to an automatic sample supply apparatus which sequentially supplies to and returns from a station for analysis or other treatment a plurality of sample vessels such as test tubes. more particularly, this invention relates to an automatic sample supply apparatus as mentioned above in which rubberstoppered sample vessels can be used and samples therein can be drawn out by a suction needle means with the rubber stopper retained in position. In this specification, the term "sampling" means drawing out liquid test samples from sample vessels and supplying the samples to an analytical apparatus, for example a vessel for analysis such as an optical cell.
2. Description of the Prior Art
U.S. Pat. No. 4,518,264, for instance, discloses an automatic sample supply apparatus which sequentially supplies to and returns from a station for analysis a plurality of sample vessels such as test tubes. In this apparatus, a plurality of test tubes, respectively accommodated in a magazine, are arranged in a waiting station, forwarded to a stirring station one by one, and then the empty vessels are returned to the waiting station after the analysis or other treatment has been finished.
In this known automatic sample supply apparatus, a plurality of test tubes are arranged upright in a matrix pattern comprised of a plurality of rows of sample vessels in a waiting station. The waiting station is provided with a means which advances a row of sample vessels as a whole in the direction of the column one row at a time and a means which feeds test tubes in the front row laterally one by one to a sample transfer means through an outlet gate provided at one end of the front row, said sample transfer means transfering the sample vessel to a stirring station. The waiting station is further provided with an inlet gate for sample vessls at one end of the back row in the waiting station, via which emptied sample vessels are returned.
Each sample vessel sent out of the outlet gate of the waiting station is transfered to a stirring station by a transfer means, and the sample is stirred. After the sample has been stirred, the sample in the vessel is transfered to an analysis station by a suction tube which is inserted into the test tube for drawing up the sample, said suction tube being operated by the orders from the analysis station.
The suction tube is then withdrawn and the empty sample vessel is returned to the vicinity of the outlet gate by the transfer means, and is then passed through the inlet gate to the back row in the waiting station by a sample-forwarding means.
Such known apparatus is characterized in that the test samples can be stirred one by one, and therefore all the samples can be analyzed under the same conditions.
However, said apparatuses are not satisfactory because the samples vessels must be kept open so that a suction tube can be freely inserted therein, and therefore the samples are susceptible to contamination, deterioration, drying, etc. in such an apparatus. Usually, a large number at a time of samples are placed in the waiting station. Therefore, after they have been arranged in the waiting station, some samples must wait for one hour to one and half hour before they are subjected to analysis, during which time they are exposed to atmosphere and thus suffer the above-mentioned undesirable influences. Moreover, samples which readily vaporize or give off toxic fumes cannot be handled by these apparatuses, because the stoppers must be kept removed.